Exogenous and Endogenous Neuroactive Biogenic Amines: Studies with Lactococcus lactis subsp. lactis

Abstract

This work demonstrates that Lactococcus lactis subsp. lactis strains that display antimicrobial activity with respect to test cultures (potential pathogens) synthesize biogenic amines. Strains K-205 and F-116 produce submicromolar amounts of dopamine and its 2,3-dihydroxyphenylalanine precursor (DOPA) in a medium that is devoid of dopamine and DOPA. It was also revealed that exogenous neuromediators such as adrenaline (epinephrine), dopamine, and serotonin stimulated the growth and antimicrobial activity of some strains at micromolar concentrations. The growth of L. lactis subsp. lactis strain 194 was threefold accelerated by all the neurotransmitters. The stimulatory effect was observed after 6 and 12 h of cultivation. Epinephrine and serotonin failed to produce a statistically significant effect on the growth of the other tested strains (K-205, 729, and F-116). Among the neurochemicals under study, dopamine exerted the maximum (40%) stimulatory effect on the antimicrobial activity of the tested strains with both gram-positive and negative bacteria. However, these strains only insignificantly influenced the growth of fungi, presumably because this process was activated by the neurochemicals.